Transcript for Keep Your New Year's Resolution With the Left Hand Diet

finally tonight here we've all heard the saying a new year, a new you. Easier said than done when it comes to our weight. Tonight the novel idea, can simply switching which hand you eat with trick your mind into eating less. Here's nutrition and wellness editor david zinczenko tonight. Reporter: American movie goers love their popcorn. But those mindless handfuls can really add up. So how can you snack less, without going snackless? To show you the secret we invited a group of people to a movie theater. Everyone in the theater was right handed, so we asked half the group to grab their popcorn with their left hand. Our goal was to observe a concept key to changing mindless eating habits. Eating in a non-standard way, like eating with your non-dominant hand, makes you think about what you're doing. Reporter: Sure enough, when the lights went up, we saw a real difference. If I would have had it in this hand it would have been much easier to snack. Reporter: We weighed the bags and found those eating with their awkward, nondominant hand ate yearly 6 percent less. That means, over a course of a year, they could lose as much as six pounds if they continued to snack like this. But wood says it's not just about what hand you use to eat. At the google offices in new york, the company found switching treats from a clear, easy to pull gravity bins to opaque containers meant that over a seven week period alone, googlers consumed 3 million FEWER CALORIES, JUST FROM M&Ms. Everyone sees these. They know they're here. You just have to put in a little more effort. Reporter: Some simple ways to trick yourself into a smaller size. David zinczenko, abc news, new york.

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